Method for continuous wet treatment of a textile web

ABSTRACT

IN A METHOD FOR THE CONTINUOUS WET TREATMENT OF A TEXTILE WEB GUIDED ALONG A ZIG-ZAG PATH IN A BATH FORMED BY A CONTINUOUS COUNTER-CURRENT OF FLOWING TREATMENT LIQUID, THE WEB IS POSITIELY GUIDED ALONG ITS PATH OF MOVEMENT THROUGH THE BATH WHILE BEING SUPPORTED IN A SUBSTANTIALLY UNINTERRUPTED MANNER ALONG THIS PATH. THE EFFECT SIMULTANEOUS BOUNDARY LAYER EXCHANGE ON BOTH SURFACES, THE BOTH SURFACES OF THE WEB ARE ALTERNATELY COMPRESSED AND STRETCHED. THE WEB IS GUIDED OVER PERFORATED ROLLERS AND, WITH RESPECT TO THE MAJORITY OF THESE ROLLERS, THE WEB HAS   A LOOPING ANGLE THEREAROUND IN EXCESS OF 180*. THE PERFORATED ROLLERS ARE ARRANGED SO CLOSE TO EACH OTHER THAT, ALTHROUGH THEY DO NOT TOUCH, THEY FORM PRACTICALLY AN UNINTERRUPTED SUPPORT FOR THE WEB. AT LEAST ONE WIDE-SLOT NOZZLE DIRECTS TREATMENT LIQUID DIRECTLY AGAINST THE TEXTILE WEB IN THE BATH. PREFERABLY, THE ROLLERS HAVE DISPLACEMENT INSERTS THEREIN TO FILL A SUBSTANTIAL PART OF THE INTERIOR OF THE ROLLERS.

Sept. 12, 1912 P. SCHROEDEIR 3,690,814

METHOD FOR CONTINUOUS WET TREATMENT OF A TEXTILE WEB Filed Feb. 26, 19703 Sheets-Sheet 1 INVENTOR.

?ETE'R 500305351 Jwflw '4 lm RTTO'RNEVS Sept. 12, 1972 P. SCHROEDERMETHOD FOR CONTINUOUS WET TREATMENT OF A TEXTILE WEB Filed Feb. 26, 19703 Sheets-Sheet z FIG.2

INVENTOR.

BY 'PETE'R HROEDER FFITO'R N EIS Sept. 12, 1972 P. SCHROEDER 3,690,814

METHOD FOR CONTINUOUS WET TREATMENT OF A TEXTILE WEB Filed Feb. 26, 19703 Sheets-Sheet 3 INVENTOR PETE-R SLHRDED 'R RTI'Q'R NEYS United StatesPatent Int. c1: B05c 3/136 US. Cl. 8-151- 4 Claims ABSTRACT OF THEDISCLOSURE In a method for the continous wet treatment of a textile webguided along a zig-zag path in a bath formed by a continuouscounter-current of flowing treatment liquid, the Web is positivelyguided along its path of movement through the bath while being supportedin a substantially uninterrupted manner along this path. To effectsimultaneous boundary layer exchange on both surfaces, the both surfacesof the web are alternately compressed and stretched. The web is guidedover perforated rollers and, with respect to the majority of theserollers, the web has a looping angle therearound in excess of 180. Theperforated rollers are arranged so close to each other that, althoughthey do not touch, they form practically an uninterrupted support forthe web. At least one wide-slot nozzle directs treatment liquid directlyagainst the textile web in the bath. Preferably, the rollers havedisplacement inserts therein to fill a substantial part of the interiorof the rollers.

BACKGROUND OF THE INVENTION Known methods for the wet treatment, such aswashing, bleaching, steaming, dyeing, impregnating, mercerizing, etc. oftextile webs, such as webs of fabrics, knits, mats,

etc., are usually based on the principle of the so-called roll vats, andhave a relatively low efficiency.

To intensify the wet treatment processes, it has been proposed tocombine repeated squeezing or extraction with repeated bilateralspraying of the textile webs. While these measures result in a certainincrease in the efliciency of the wet treatment, they entail aconsiderable disadvantage that the textile material, subjected to thesetreatments, undergoes heavy mechanical stress, so that these methods areout of the question for delicate textiles. Also, the bath consumption isdisproportionately high. Furthermore, in

many cases it is not desirable that the textile material come in contactwith the atmosphere during the treatment,

I as is the case with this proposaldeflecting rollers, and charging it,during its passage between the rollers, with a treatment liquid,preferably from spray pipes.

In another known method, the textile material is immersed in thetreatment bath during the entire treatment. In this procedure, it issought to intensify the effect of the bath on the textile material invarious ways, for example in that a flow of the bath is produced to runcounter to the direction of movement of the textile web, or byvibrators, etc.

:In the known methods, or in the apparatus developed for practicing themethods, the webs are moved through the bath in insupported relationover long distances, and this precludes the treatment of very delicatefabrics as well is very often required.

For such a wet treatment of textile webs, it must be noted, for onething, that it is determining, for the quality of the treatment, thatthe bath concentration be distributed as evenly as possible over thewidth of the textile web. This can be attained by bath turbulence orthrough mixing, for example cycling of the treatment bath. Anotherproblem is to get the treatment liquid really to the fiber or into thefiber. The bath particles must essentially pass through two zones,namely at first the boundary layer around the moving fiber and then, inthe case of cotton, the actual fiber walls or, in synthetic material,the homogenous fiber. The penetration of these zones occurs bydiffusion. Such diffusion processes are known to be relatively slow andto have a disadvantageous effect on the economic efiiciency of aninstallation. It has therefore been tried to shorten the treatment timesas much as possible.

On the basis of Ficks first law of diffusion, it is found that the rateof diffusion is proportional to the concentration gradient. Ficks law ofdiffusion may be stated as follows:

wherein dm=diffusing quantity F=surface to be traversed dt=diffusiontime dx=diffusion path dm/Fdt=rate of diffusion D=diffusion constantdc/dx: concentration gradient dc=concentration difference.

To obtain as favorable as possible a solution in terms of engineering,an attempt must be made to influence the values on the right side of theabove equation in such a way that the entire expression becomes amaximum. However, such maximization of the rate of diffusion must notsimultaneously lead to high operational costs, but should result in anincrease of efficiency. The concentration gradient dx/dx can be made amaximum, from the beginning to the end of the process, if theconcentration difference between the bath and the fabric is continuouslymaintained at as high as possible a value. It follows from this that thetextile web must, during the entire process, be immersed in the bath,and the bath must be guided in a continuous counter-current relative tothe textile web. This results in a single-bath process.

In order for economic reasons, to make the diffusion paths dx as shortas possible, the moving bath must be applied directly on the individualfibers, in order that the concentration difference between the surfaceand the interior of the fiber will become a maximum and the respectivechemicals can diffuse quickly, However, since the fabric web moving inthe liquid has a relatively thick boundary layer, it is necessary tobreak through this layer as quickly and as thoroughly as possible toobtain the desired treatment effect.

SUMMARY OF THE INVENTION This invention relates to the continuous wettreatment of textile webs and, more particularly, to an improved methodand apparatus for such treatment which, while handling the web to betreated extremely gently, insure an effective penetration of theboundary layers of the web.

The method and apparatus of the invention provide an increase in theefficiency of the treatment and, thus, a substantial shortening of therequired treatment time is attained while, at the same time, theinvention method and apparau's provide the possibility of treatingextremely delicate webs without danger of damaging the webs.

In the invention method, the textile web, while passing through thetreatment bath, is guided positively and supported practically withoutinterruption. For the purpose of simultaneous boundary layer exchange onboth surfaces of the Web, the opposite surfaces are alternatelystretched and compressed by an alternating bending motion.

The apparatus for performing the method comprises rollers arranged in achannel-type bath vessel and providing a zig-zag deflection of thetextile web. The rollers are perforated and are arranged so closetogether that, while they do not touch, they form practically anuninterrupted support for the textile web.

An object of the invention is to provide an improved method for thecontinuous wet treatment of textile webs.

Another object of the invention is to provide an improved apparatus forthe continuous Wet treatment of textile webs.

A further object of the invention is to provide such a method andapparatus in which the web can be treated extremely gently whileinsuring an effective penetration of the boundary layers of the web.

Another object of the invention is to provide such a method andapparatus increasing the efficiency of the treatment and decreasing therequired treatment time.

A further object of the invention is to provide such a method andapparatus capable of treating extremely delicate webs without danger ofdamage.

For an understanding of the principles of the invention, reference ismade to the following description of typical embodiments thereof asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional viewthrough one form of apparatus for performing the method of theinvention;

FIG. 2 is a vertical sectional view through another form of apparatusembodying the invention; and

FIG. 3 is a vertical sectional view through still another embodiment ofthe apparatus for performing the method of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, asubstantially U-shaped upright vessel 1 accommodates the maximumpossible number of rotatable rollers 2 and 3. These rollers are arrangedin the two vertical legs of the vessel in the form of two rolls ofrollers which are staggered relative to each other. All of the rollers 2and 3 have perforated surfaces, so that treatment liquid can reach thetextile web from both sides. Additionally, the perforations preventbuilding up of a liquid cushion between the textile web 14 and therollers 2 and 3, which buildup would increase the tension in the fabricsince the effective circumference of the rolls thereby would beincreased.

The arrangement of the rollers 2 and 3 is so selected that they are asnear together as possible without touching, so that the free path oftextile web 14 between two rolls become so small that web 14 passesthrough the apparatus supported practically without any interruption.Textile web 14 is guided around rollers 2 and 3 in meander form, and ispassed through the apparatus, filled with treatment bath, in thedirection of the arrow and treated by the bath during such passage. Asthe rollers 2 and 3 are very close together, the looping angle becomesrelatively large and, for most of the rolls, exceeds 180.

Through this special positive guiding of textile web 14 by rollers 2 and3, there results, by virtue of the alternately opposite deflection ofthe textile web, an opening and a closing, which is particularlyimportant for the penetration of the treatment liquid through theboundary layers of the web, in that, with the curvature of the fabricweb, the fiber interstices on the inner side are closed and the liquidpresent therein is squeezed out. At the immediately following subsequentdeflection, textile Cit web 14 is deflected in the opposite directionand the previously closed interstices are now opened. The external fiberinterstices are thereby enlarged and draw in liquid from the outside.

In this boundary layer, which with the usual roughness is relativelythick, there thus results an exchange flow extending between the fibersurfaces and the boundary layer surfaces. Thereby, the desiredconcentration gradient is produced directly at the fiber surfaces, incontrast to conventional apparatus wherein the treatment bath at thefiber surfaces has approximately the same concentration as in the fibersthemselves, and it is only toward the outer limitations of the boundarylayer that there is a concentration difference with the surroundingbath. With these conventional machines, however, the effect of thetreatment bath within the relatively thick boundary layer can occur onlythrough a relatively slow diffusion.

The boundary layer penetration is additionally enhanced by the provisionof several wide-slot nozzles 4. In view of the relatively high energyconsumption needed for operating these nozzles, their use is limited toa small number.

In order that textile web 14 will have as low as possible a tensionduring the treatment process, all of the rollers 2 and 3 of theapparatus are driven slip-free, for example by means of chains, so thatall rolls necessarily always have the same speed or angular velocity. Inaddition, the tension between feed roller 5 and other rollers 2 and 3,including the squeeze rollers 6, is controlled by a dancer roll 7.

The supply of the bath in counter-current to the direction of webmovement is effected through the wide-slot nozzle 8 positioned directlybelow squeeze roller 6, while the other wide-slot nozzles 4 are fedthrough a line 10 and produce a circulation of the treatment liquid.

To insert the textile web, walls 11 may be removed. Rollers 2 and 3 aredesigned as tubular rollers and containing in their interior,displacement bodies 12, whereby the required bath quantity is reducedand, in addition, the treatment bath is channeled.

Turning now to FIG. 2, the apparatus shown therein is suitablepreferably for neutralizing or impregnating, and is of somewhat simplerdesign. However, the basic method of operation is the same as in theembodiment shown in FIG. 1. In contrast to the embodiment shown in FIG.1, in FIG. 2, a relatively high, upright roll-free inlet and outletchannel means 16 and 17 is provided.

In the embodiment of the invention shown in FIG. 3, the entrance fortextile web 14 is provided at the lower end of the vessel. This effectsthe good seal at the introduction point. The number and arrangement ofthe rollers depend on the intended treatment process and on the textilematerial to be treated.

The arrangement of the rolls also may be selected 'so that the textileweb passes substantially horizontally or otherwise through the vessel.In particular, for example,

- for a vessel having'a U-shaped vertical section, a possiblearrangement is one Where the rollers form a row with their axes side byside.

It is also possible to close the vessel at the top and to put it underpressure, for example by compressed air, whereby the apparatus may beoperated at bath temperatures of over C.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. In a method for the continuous treatment of a textile'web guidedalong a zig-zag path in a bath formed by a continuous counter-current offlowing treatment liquid, the improvement comprising the steps ofguiding the web positively along its path of movement through the bathwhile providing substantially uninterrupted support for the web alongits path of movement; alternately compressing and stretching bothsurfaces of the web to eifect simultaneous boundary layer exchange onboth surfaces, and directing at least one jet-like stream of treatmentliq uid against said web within the bath at an angle relative to thegeneral direction of movement of the web through the bath.

2. In a method for the continuous wet treatment of a textile web, theimprovement claimed in claim 1, includ ing the step of guiding the webover perforated rollers with the majority of the rollers having alooping angle, of the web, in excess of 180.

3. In a method for the continuous wet treatment of a textile web whichis moved in meander-like manner through a vessel through which treatmentliquid is forced in counter-current to the direction of movement of theweb and wherein treatment liquid is additionally applied to the surfaceof the moving web to penetrate the web, the improvement which comprisesthat said additionally applied treatment liquid is directed against theweb surface within the bath in the form of a jet-like stream at an acuteangle relative to the direction of movement of the web through thevessel.

4. The improvement of claim 3, wherein said jet-like stream of treatmentliquid causes or assists the countercurrent flow of the treatment liquidthrough the vessel.

References Cited UNITED STATES PATENTS 3,439,365 4/1969 Bahnsen 68-203,457,740 7/1969 Korsch 68-43 X FOREIGN PATENTS 655,302 12/1928 France6843 378,835 8/1964 Switzerland 68-43 579,622 6/ 1933 Germany 68-175437,183 11/ 1967 Switzerland 68-43 931,182 9/1947 France 68-43 337,71211/1930 Great Britain 68-43 WILLIAM 1. PRICE, Primary Examiner US. Cl.X.R.

